The present invention relates in general to improved head assemblies for reading/writing data on a storage medium, and particularly, to a magnetic head assembly for use with a flexible magnetic storage medium. This invention also relates to actuators and disk drives that employ the improved head assemblies.
Disk drives of the type that receive a disk media having a data storage medium typically have a head assembly for communicating with the storage medium. The storage medium may be disc shaped, and if so, the data storage cartridge may be referred to as a disk cartridge. The data storage medium may be of the type that is removable from the disk drive, and if so, it may be referred to as a removable disk cartridge. The head assembly may include a pair of sliders. Each slider is typically mounted on an actuator that is mounted within a disk drive. Additionally, each of the sliders may have a read/write head for interfacing with a storage medium of a disk cartridge. The sliders are also commonly referred to as read/write heads.
Generally, the actuator on which the head assembly is mounted moves between a retracted position and an interfacing position. In the retracted position, the heads are disposed in a position that minimizes the likelihood of damage to the heads from either dynamic or static forces. When a disk cartridge has not been inserted into the disk drive, the actuator holds the heads in this retracted position. When a disk cartridge is inserted into the disk drive, the actuator moves the heads to the interfacing position. In the interfacing position, the actuator is in a position in which the heads can interface with the storage medium that has been inserted into the disk drive.
The storage medium with which the head assembly may interface may have a top surface and a bottom surface. Preferably, in the interacting position the storage medium is disposed between the sliders of the head assembly. One of the sliders may be disposed proximal to the top surface, and one of the sliders may be disposed proximal to the bottom surface. In operation, the storage medium of the disk cartridge is rotated between the sliders and an air bearing is created between the storage medium and the sliders. As the storage medium is rotated, the heads xe2x80x9cridexe2x80x9d on these air bearings and the heads interface with the storage medium.
The design of head assemblies is significant because it affects the ability of the heads to interface with the storage medium of the disk drive. In particular, the ability of the heads to interface with the storage medium is a function of the spacing between the sliders and the storage medium. The spacing between the sliders and the media is important because it affects the ability of the disk drive to communicate with the media. Ordinarily, the sliders fly very low with respect to the media. As the distance between the media and the sliders increases, the signal degrades. With the development of higher density media, it is desired to develop sliders that have even lower fly heights then those previously developed.
For instance, one of the concerns when designing head assemblies is that the spacing between the read/write heads and the storage medium be relatively constant. If the spacing between the read/write heads and the storage medium is not relatively constant, this can cause a degradation in the ability of the heads to interface with the storage medium. The importance of maintaining the spacing between the storage medium and the heads relatively constant is even more pronounced in disk cartridges that have storage mediums with a relatively high density.
In order to maintain an appropriate spacing between the read/write heads and the storage medium, the air bearing created between the slider and the storage medium must be relatively constant. At high speeds, the flexible storage medium tends to flutter and therefore the importance of maintaining the spacing between the read/write heads and the storage medium is even more pronounced at high speeds. In addition to being dependent on the speed of rotation of the storage medium, the air bearing is a function of the geometry of the head assemblies and the storage medium. Therefore, the geometry of these components is of particular importance.
In addition to affecting the performance of the head assembly, the spacing between the head assembly and the storage medium also affects the life of both the read/write heads and the storage medium. For instance, if the storage medium fluctuates, the storage medium and the heads may wear unevenly and their respective lives may be reduced. Furthermore, if the air bearing pressure is relatively high, the storage medium and the heads will wear at a faster rate. The amount of fluctuation of the storage medium is a function of the geometry of the head assembly and the storage medium. Manufacturing imperfections in the design of head assemblies and variations in head assemblies due to large design tolerances have the potential to cause an imbalance of forces between the head assembly and the storage medium and subsequent fluctuations of the storage medium. Therefore, it is important to design head assemblies, so that the manufacturing tolerances are relatively low and the likelihood of manufacturing imperfections are reduced.
Previous designs of magnetic head assemblies are exemplified in U.S. Pat. No. 5,636,085 (Jones et al.), entitled xe2x80x9cMagnetic Read/Write Head Assembly Configuration With Bleed Slots Passing Through Rails To Stabilize Flexible Medium While Attaining Low Fly Heights With Respect Thereto,xe2x80x9d and U.S. Pat. No. 4,974,106 (White et al.), entitled xe2x80x9cNon-Contact Magnetic Head Assembly For A Flexible Medium Disk Drive.xe2x80x9d Jones et al., which is also owned by the assignee of the invention described in this application, and White et al. both describe magnetic head assemblies. The inventions described in these patents are directed to improved magnetic head assemblies, but may be used with other types of head assemblies such as optical head assemblies.
Recently, higher density storage media has been and is being developed. Previously, the Iomega Zip(copyright) disk cartridge was considered to have a relatively high density. Even higher density magnetic media are being developed. The sliders and head assembly disclosed in the Jones et al. patent was designed to interface with the magnetic media, such as the Zip(copyright) 100 disk cartridge. Although the sliders taught by Jones et al. have been sufficient for use with disk cartridges that have the density about equal to that of the Zip(copyright) 100 disk cartridges, the advent of higher density magnetic media requires sliders that can better communicate with higher density media.
The sliders, described in Jones et al., have a relatively low fly height. However, this fly height has proven to be too great for operation with higher density media. The head assembly of this invention improves upon that of Jones et al. to improve the ability of the disk drive to communicate with higher density media.
In addition, contaminants entering the high contact-pressure zone of the head-disk interface can also lead to decreased performance of the head assembly due to increased spacing. Contaminants that may be introduced into the cartridge can cause decreased performance of the cartridge by, for example, increasing the spacing between the heads and the disk surface (e.g., fly height), producing phantom writes, damaging the heads, and/or damaging the media surface, etc., all of which are undesirable. In this respect, the disk cartridge is preferably designed in such a way so as to minimize the possibility of contaminants entering the cartridge. Nonetheless, unless it is sealed, contaminants will eventually enter the cartridge.
In order to reduce the introduction of contaminants into the cartridge, the housing typically includes a door arrangement which closes over the aperture when the disk drive cartridge arrangement is not in use to prevent contamination from entering the housing, such as when the cartridge is removed from the disk drive unit. However, during operation the door arrangement is typically opened to allow the read write heads to access the disk and this may allow contaminants to enter the housing.
In addition, as the disk spins, an air flow is generated by the spinning disk and air flows axially and tangentially over and off of the surface of the spinning disk. This air flow creates an area of low pressure (e.g., a vacuum) proximate a center region of the disk in the area of the disk hub. This low pressure area creates a second flow of air from outside the housing into the disk housing through the space between the hub and the hub opening. This flow of air into the housing through the space around the hub opening may introduce contaminants into the housing.
Therefore, a need exists for air bearing features on magnetic head assemblies for controlling contaminants that may have been introduced into the cartridge from entering the high contact-pressure zone of the head-disk interface.
According to this invention, an improved head assembly has a first and a second slider for interfacing with a data storage medium of a data storage cartridge. The second slider is preferably disposed below the first slider. The data storage cartridge with which the head assembly of this invention may be employed may be a disk cartridge of the type that can be inserted and ejected from a disk drive. However, the head assembly of this invention may be employed with other types of data storage cartridges. The head assembly may be a magnetic head assembly and be employed with a flexible magnetic data storage media. However, the head assembly of this invention is not so limited and may be employed with other types of data storage media, such as optical media and hard disk media. Moreover, the head assembly of this invention may be employed with a variety of types of disk drives, such as, a scanner disk drive, a camera disk drive, a computer disk drive, and the like. These examples are not intended to be limiting.
According to one embodiment of the present invention, the improved head assembly includes a first and a second slider that each have a pair of longitudinal rails. These rails preferably extend parallel to the longitudinal axis of the respective slider. Both the first and the second sliders have a shaped slot air bearing feature formed in one of their longitudinal rails. The shaped slot air bearing feature in the longitudinal rail of the sliders is preferably an X-shaped slot having an entrance point and an exit point on each side of the rail. In one embodiment, the shaped slot air bearing feature is positioned in a central region of the rail. In an alternative embodiment, the shaped slot air bearing feature is positioned proximate the area containing the sensor. In another embodiment, a plurality of shaped slot air bearing features are formed along the longitudinal length of the rail with at lease one shaped slot air bearing feature positioned in the center region and at least one shaped slot air bearing feature positioned proximate the sensor. The sliders may be disposed in the disk drive such that the longitudinal rails of each of the sliders are aligned. Preferably the longitudinal rail having the shaped slot air bearing feature of each of the sliders is aligned with the longitudinal rail of the other slider that does not have a shaped slot air bearing feature. As described, a storage media may be disposed between the sliders.
In another embodiment of the present invention, a shaped rail air bearing feature is provided on the second rail, or the rail that does not have the sensor. Preferably, the shaped rail air bearing feature includes a L-shaped rail having a longitudinal portion and a transverse portion extending along the leading edge from the longitudinal portion to a free distal end. Preferably, the leading edge of the transverse portion has a shaped leading edge, such as a bevel, a ramp, or a step. An opening is formed between the transverse portion and the first rail. The L-shaped rail creates an area of low pressure behind the transverse portion thereby causing contaminants to flow toward the longitudinal portion of the shaped rail and away from the sensor and the head disk interface.
In another embodiment, the shaped rail air bearing feature can include skives formed at the second rear end of the longitudinal portion to further help control the flow of contaminants and also to provide a good contact with the sensor of the opposed slider.
In another embodiment, the shaped rail air bearing feature can include a ledge formed extending between the distal end of the transverse portion and the longitudinal portion to help control the flow of contaminants by the shaped rail. The height and shape of the ledge can be adjusted based on the application to influence the extent of a sub-ambient pressure zone formed by the shaped rail thereby further controlling the flow of contaminants away from the sensor.
Each of the sliders preferably may have a read/write sensor disposed on an end of at least one of its longitudinal rails. Preferably, the sensor is disposed in the longitudinal rail of the slider that has the shaped slot air bearing feature. Through this sensor the head assembly can communicate information between the data storage media and, for example, a microprocessor. A high contact-pressure zone, or low fly-height zone, is formed within the head disk interface where the sensor communicates with (contacts) the disk. The head disk interface generally includes a whole set of concerns, such as the ABS, shape, contour, slider material, media dynamics, surface parameters, wear characteristics, contaminant control, lubrication, and the like. The high contact-pressure zone, or low fly-height zone, generally includes the portion of the rail where the sensor is located and where the head assembly is contacting the media or flying at its lowest fly-height over the media. In a preferred embodiment, the head assembly is a magnetic head assembly that has an electromagnetic sensor for communicating with a flexible magnetic data storage media.
Each of the sliders preferably has a leading edge and a trailing edge. The leading edge is that which leads the sliders into the direction of rotation of the storage medium, and the trailing edges are that which trail the direction of motion. Preferably, the leading edge has a shape, such as a bevel, a ramp, or a step, and the trailing edges is beveled. The sensor is preferably disposed proximal to the trailing edge of the sliders in the high contact-pressure zone or low fly height zone.
The head assembly of this invention may be disposed on an actuator within a disk drive. In a preferred embodiment of this invention, the head assembly is disposed on a rotary type of actuator, and in an alternative preferred embodiment the head assembly is disposed on a linear type of actuator. The actuator is preferably moveable between a retracted position and an interfacing position. In the retracted position, the head assembly is retracted relative to the area in which the disk cartridge rests within the disk drive when the disk cartridge is inserted into the disk drive. When a disk cartridge is inserted into the disk drive, the actuator may be moved to the interfacing position. In the interfacing position, the head assembly of the actuator is disposed proximal to the storage medium of the disk drive. More particularly, the storage medium may be disposed between the first and the second slider, so that the first slider is disposed proximal to a first surface of the storage medium and the second slider is disposed proximal to a second surface of the storage medium.
The storage medium is preferably rotated as it rests between the first and the second slider. As the storage medium rotates, an air flow (e.g., an air bearing) is created between the first surface of the storage medium and the first slider and the second surface of the storage medium and the second slider. This air flow creates an air bearing between the first surface of the storage medium and the first slider and the second surface of the storage medium and the second slider.
The air bearing features formed in the head assembly of the present invention provide for contaminant control in the flexible media at the sensor location within the high contact-pressure zone or low fly-height zone. The shaped slot and shaped rail air bearing features help direct contaminants away from the sensor, thereby improving the performance of the head assembly. Other advantages described below may also be achieved by controlling contaminant flow in the flexible media away from the sensor.
In a preferred embodiment, the head assembly is a magnetic head assembly that interfaces with a magnetic data storage media. The head assembly may also be used for optical communication with optical data storage media. In addition, the head assembly having air bearing features for controlling a flow of contaminants away from the sensor may be used with flexible, semi-rigid, and rigid media.
Other features of the invention are described below.
The foregoing summary, as well as the following detailed description of the preferred embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings embodiments that are presently preferred, it being understood, however, that the invention is not limited to the specific methods and instrumentalities disclosed. In the drawings:
FIG. 1 is a diagrammatical view of the head assembly according to a preferred embodiment of this invention with a storage medium of a disk cartridge;
FIG. 2 is an isometric view of a portion of the head assembly of FIG. 1;
FIG. 3 is a top view of the portion of the head assembly of FIG. 2;
FIG. 4 is a diagrammatical view of the operation of the head assembly of FIG. 1;
FIG. 5 is a top view of another preferred embodiment of the head assembly of FIG. 1;
FIG. 6 is a top view of another preferred embodiment of the head assembly of FIG. 1;
FIG. 7 is a top view of another preferred embodiment of the head assembly of FIG. 1;
FIG. 8 is a top view of another preferred embodiment of the head assembly of this invention;
FIG. 9 is a top view of another preferred embodiment of the head assembly of this invention;
FIG. 10 is a cross section taken along line 10xe2x80x9410 of FIG. 4;
FIG. 11 is a diagram illustrating the operation of the head assembly of FIG. 1;
FIG. 12 is a graph comparing the operation of the head assembly of this invention with a prior art head assembly;
FIG. 13 is a top view of another embodiment of the head assembly of FIG. 1 having a shaped slot air bearing feature;
FIG. 14 is a top view of another embodiment of the head assembly of FIG. 1 having a shaped slot air bearing feature formed proximate the sensor;
FIG. 15 is a top view of another embodiment of the head assembly of FIG. 1 having a plurality of shaped slot air bearing features formed both on the rail and by the sensor;
FIG. 16 is a top view of another embodiment of the head assembly of FIG. 1 having a shaped rail air bearing feature;
FIG. 17 is a top view of another embodiment of the head assembly of FIG. 16 having skives;
FIG. 18 is a top view of another embodiment of the head assembly of FIG. 17 having a ledge;
FIGS. 19A, 19B, and 19C show exemplary contaminant flows formed under the head assembly of the present invention having a shaped slot air bearing feature for controlling a flow of contaminants away from the sensor;
FIGS. 20A, 20B, and 20C show another exemplary contaminant flow formed under another head assembly in accordance with the present invention for controlling a flow of contaminants away from the sensor;
FIGS. 21A, 21B, and 21C show another exemplary contaminant flow formed under another head assembly in accordance with the present invention;
FIGS. 22A, 22B, and 22C show another exemplary contaminant flow formed under another head assembly having a shaped rail air bearing feature for controlling a flow of contaminants away from the sensor;
FIGS. 23A, 23B, and 23C show another exemplary contaminant flow formed under the head assembly of FIGS. 22A, 22B, and 22C further including skives; and
FIGS. 24A, 24B, and 24C show another exemplary air bearing formed under another head assembly of FIGS. 22A, 22B, and 22C further including a ledge.